DNA is a primary target for many chemical agents which have been implicated as environmental hazards. Unless repaired prior to replication, DNA-damaging events may lead to mutation or other genetic damage. We propose to establish a Specialized Center of research in Genetic Toxicology that will focus on the chemistry and molecular biology of DNA adducts in mammalian cells. Research conducted in this Center will explore the molecular toxicology of adducts derived from important classes of environmental mutagens. Chemicals to be studied initially include benzo(a) pyrene, aromatic amines and several potent mutagens isolated from fried foods. The mutagenic properties of pyrimidine dimers, modified nucleosides and DNA containing apurinic/apyridinic sites will also be examined. Research projects will utilize oligodeoxy-nucleotides that have been selectively modified with chemical mutations or their active metabolites. These modified oligonucleotides, prepared by organic synthesis, will be used to explore short-and long-term consequences of adducts bound to a defined fragment of DNA. The interaction of DNA and RNA polymerases with chemically-modified DNA primers and templates will be studied and the ultimate effects of these changes on replication and transcription will be determined. Longer-term effects of chemical damage to DNA will be studied by examining patterns of mutations produced during repair and replication of modified DNA. Finally, monoclonal antibodies will be raised against selected DNA adducts. These antisera will be characterized and used to develop sensitive and specific immunological assays for the detection and quantitation of mutagens and adducts in biological samples.